生物质化学组分在空气和合成气下的热重行为研究

Thermogravimetric behaviors of biomass′ chemical components under air or syngas

在热重分析仪上,分别在空气和合成气气氛下,对生物质三种化学组分(纤维素、半纤维素和木质素)的热重行为进行了研究,考察了两种不同气氛下生物质及其三种组分的热化学转化温度区间分布;同时通过合成样品(以不同比例混合的三种组分的混合物)热重曲线的实验值和理论计算值的对比分析,考察了生物质化学组分在不同气氛下热重行为的相互作用。结果表明,在空气和合成气气氛下生物质各种化学组分发生热化学反应从难到易的顺序为木质素>纤维素>半纤维素,这是由其不同的化学结构决定的,但不同气氛下各组分的具体热重行为存在一定差别。在合成气气氛下木质素及半纤维素在与纤维素的共热解过程中存在明显的协同作用,而在空气气氛下半纤维素及纤维素在与木质素的共燃烧过程中存在一定的协同作用,这与各组分在不同气氛下所处的热化学反应温度区间具有一定的关系。

The thermogravimetric behaviors of biomass＇ chemical components （ cellulose, hemicellulose and lignin） were studied in a thermogravimetric analyzer （TGA92） under air or syngas. The decomposing temperatures of the three components were examined. In order to understand the interaction between the three components, the synthesized samples （a mixture of these components with different ratios ） were tested. Meanwhile, the experimental and calculated TG and DTG profiles were compared. The results show that both under air and syngas, among the three components, hemicellulose is the easiest one to be decomposed, while lignin is the most diffieuh one. Under different atmospheres the thermogravimetric behavior of each component is different. Both lignin and hemicellulose will affect the pyrolysis characteristic of cellulose under syngas, while both cellulose and hemicellulose will affect the combustion characteristic of lignin under air, which are related to the range of decomposing temperatures.